thanks for the suggestions bmw put it on computer....you were right...the o2 sensor has seen better days.
however....im not confident its my only problem...i have just replaced the thermostat because it was blowing cold air and over heating on longer runs.
seemed to fix the problem.....but its back again....the car overheated today on the way back from silverlink......and blew cold air.
also its running very poorly....no power.....and it hicks and farts.
at my wits end with it....i dare not drive it any distance.....and i fear it may be the cylinder head.
the revs are still up and down.....lots of soot still out the exhaust.
ive checked rocker cover and dipped oil....does not seem to be any water in there and its not loosing any water or oil.
if you can suggest anything i would greatly appreciate it.
im very attached to the car and dont want to get rid